As a gasket for sealing a gap between two members, there has been known one that is mounted in a groove formed in one of the two members. Such a gasket exerts sealing performance by being made into close contact with the two members, respectively, under the action of a repulsive force which is produced when the gasket is compressed by the two members.
Here, in cases where either one of the two members is composed of a material of low rigidity, it may be deformed when the repulsive force of the gasket is too large. As a result, defects such as reduction in sealing performance will arise. Accordingly, in order to make the repulsive force smaller, a measure is taken in which the width of the gasket in a state of being not clamped or sandwiched by the two members is constructed to be narrower than the width of the groove.
In the case of such a gasket, the gasket may fall or buckle in the groove. As a result, it is difficult to stabilize the posture of the gasket, so it is an important problem how to stabilize the posture. For example, in order to stabilize the posture of the gasket, the cross sectional shape of the gasket is made to be right-left asymmetry. Thus, there has been known a technique in which with such a shape, the gasket is made liable to fall in a desired direction at the time of compression thereof, so that the posture of the gasket in the groove is thereby stabilized (see a first patent document).
However, it may be difficult to make the gasket fall so as to take a desired posture, and hence it is much more desired to attain stabilization of the posture of the gasket in the groove. In addition, in the case of a gasket the width of which is narrower than the width of the groove, in an assembly operation, the gasket is liable to come out of the groove. For this reason, it is also desired to adopt a construction in which the gasket does not come out of the groove.